Electromagnetic interference (EMI), also known as radio frequency interference (RFI), is an unacceptable electromagnetic disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. Electromagnetic noises may be natural noises (e.g., lightning and static electricity) or artificial noises (e.g., contact noise, leaking from high frequency devices, etc). The disturbance may results in the degradation or malfunction of electronic or electrical equipment. Major sources of EMI include microprocessors, switching power supplies, AC motors, and electrical power cords.
EMI filters are passive electronic devices that are used to suppress conducted interference that is found on a signal or power line, including interference created by other equipment, as well as the interference of the system itself, resulting in improved immunity from EMI signals in the surrounding setting.
An EMI filter may comprise of multiple components including inductors (or chokes) and capacitors. An inductor may comprise insulated conductive wire wrapped around a toroidal magnetic core. The current is passed through the conductive wire from a power source and then onto a load. The passing current causes the inductor to heat up, especially at higher amperes (amps). High temperatures can reduce performance and/or efficiency of the electronic device, as well as cause damage to the device and the filter choke itself.
Standard methods for insulating and maintaining proper operational temperatures of EMI filters is achieved by encasing the filter in an electrical potting material and blowing cold air over the surface. However, as the space for electrical components decreases, it becomes increasingly difficult to maintain desired temperatures through airflow alone. Thus, there is a need for cooling an inductor of an EMI filter operating at high voltages in a closed space.